Development in numerical modeling and evaluation of hazard for slope deformation and failure

崩塌和崩塌对区域内的道路和设施造成严重危害。这项研究的目的是建立一个程序，使用数值模拟来评估处于危险中的区域。本文介绍了(1)崩落和(2)渐进式破坏的数值模拟方法。(1)采用弹簧-滑块-阻尼器系统来模拟巨石冲击斜坡时产生的弹跳现象。用系统的微观性质(k_n，k_t，η_n，η_t)和动力学条件表示恢复系数的法向分量和切向分量(R_&lt；en&gt；，R_&lt；et&gt；)。结果表明，R&lt；Et&gt；随入射角的增大而增大，新开发的程序能够捕捉到R&lt；Et&gt；的增加。在不同的空间分辨率下，使用由平均倾角和局部粗糙度表征的合成双平面斜坡集进行了参数模拟。通过三维数值模拟，评价了控制因素对落石弹丸散布的影响。建立了基于离散元分析的边坡渐进破坏数值模型。数值模拟分为两个阶段。第一步是得到具有单元间粘结效应的圆形刚性单元合成试件的力学性能。二是对一个缩尺岩质边坡在重力作用下的变形进行了分析。在合成试件的标定性质不变的情况下，显示了边坡模型中位移的演化和由此产生的破坏面的起始。该模型可以根据岩石边坡的几何数据和强度特性，如粘聚力、内摩擦角等，给出岩石边坡可能的破坏体积。

Rockfall and slope failure pose serious hazards to roads and facilities in regional areas. The aim of this study is to build a procedure to evaluate the zone at risk using numerical simulation. This paper reports numerical procedures for (1) rockfall and (2) progressive failure in slope.(1) This study has adopted a spring-dashpot-slider system to model the bouncing phenomenon, occurring when boulders impact on the slope. The normal and tangential components (R_<en>, R_<et>) of restitution coefficient are expressed using the micro-properties (k_n, k_t η_n, η_t) of the system and the kinetic conditions.A small-scale free-fall-rebound test using a sphere boulder in laboratory was conducted. The results show that R_<et> increase with the ncrease of the incoming angle and the newly developed program can capture the increase of R_<et>. Parametric mulations have been performed at different spatial resolutions using sets of synthetic biplanar slopes haracterized by mean inclination and local asperities. The influence of controlling factors on the dispersion of rockfall rajectory has been evaluated by conducting 3D simulation. Finally, a rockfall encounter analysis is proposed using he numerical method developed in this study.(2) A numerical modeling of progressive failure in slope using the distinct element analysis has been developed. The numerical modeling consists of two stages. The first is to get the mechanical properties of synthetic specimens omposed of circular rigid elements with the bonded effect between elements. The second is to analyze deformation of a reduced-scale rock slope under the gravity increased condition. With the calibrated properties of the synthetic specimen being unchanged, evolution of displacements and the resulting initiation of failure surface in the slope odel are displayed. The modeling can give a possible failure volume of rock slope based on the geometrical data and strength properties, such as cohesion and internal friction angle.